function out = int_alpha(alpha, r, r_, theta )
%INT_ALPHA Summary of this function goes here
%   Detailed explanation goes here

global A;

%disp(['alpha= ' num2str(alpha)]);
%disp(['r= ' num2str(r)]);
%disp(['r_= ' num2str(r_)]);
%disp(['theta= ' num2str(theta)]);

out = A( sqrt( r_.^2 .* (1-alpha).^2 + alpha.^2 .* r.^2 + 2 .* alpha .* (1-alpha) .* r .* r_ .* cos(theta) ) );

end

